SRV, which is an abbreviation for Service, is a DNS record, which allows you to use a domain for a particular service different from an Internet site. By setting up a couple of SRV records, you are able to use the domain address with different companies and direct it to a number of servers at a time, each and every server managing a different service. You'll be able to specify the port number for the connection to every machine, so there won't be any interference. You can even set different priorities and weight for two records which are used for the same service, but point to different servers for redundancy or load balancing. With an SRV record you can use your domain name or a subdomain under it for a Voice-Over-IP server, for example, and have the real software running on several machines with different companies. Which one a client of yours will use depends on the priority and weight values that you've set.